Mulgan. — The Waitemata Series. 4<15 



form a valuable factor in correlating different parts of the 

 series, and hence the importance of determining whether 

 there are several bands of grit or only one, and whether, 

 moreover, the material is due to air-borne or water-borne sedi- 

 ment. It is important also to locate as nearly as possible the 

 position of the vents from which the material originated. 



The microscopic appearance of the sections as shown in 

 the plates will facilitate the comparison of the rocks under 

 discussion. 



Section II. — Literature. 



Dr. Von Hochstetter, in 1859, stated that beds of volcanic 

 ashes were interstratified with the sedimentary rocks occur- 

 ring on the shores of the Auckland Harbour. Subsequently, 

 in 1861, he made the same statements, and also alluded to 

 the remarkable blocks of volcanic rock which occur on the 

 Whangaparaoa Peninsula interbedded with the stratified de- 

 posits. 



Twenty years later, in 1879, Mr. S. H. Cox, late Assistant 

 Geologist, reported on the country from Auckland northwards. 

 The whole of the Waitemata series as developed round Auck- 

 land and to the north of that city he placed as'equivalents of 

 the Pareora beds and of Lower Miocene age. In his report 

 he says, " Above these beds (Orakei Bay beds) the Parnell 

 grit comes in interstratified with sandstone and thin beds of 

 sandy marl ; and this grit, together with a certain quantity of 

 volcanic ash and occasional angular stones, represents the 

 commencement of the volcanic outburst which, while some of 

 the ash and smaller stones were spread far and wide over the 

 sea-bottom on which the Waitemata series was deposited, 

 attained its greatest development near the Manukau Heads, 

 where beds of breccia at least 700 ft. and probably more in 

 thickness may be seen resting in direct sequence on the 

 marls, &c, of the Waitemata series, the higher beds of this 

 series being notable for the great abundance of volcanic 

 material which is mixed with the sand and clay. It seems 

 probable that the volcanic activity which must have prevailed 

 during the latter part of the deposition of the Waitemata beds, 

 and the consequent rapid accumulation of material on the 

 sea- bottom, may account for the great absence of animal life 

 during the latter part of this period." 



In 1881 the same writer, in a second report on the country 

 north of Auckland, endeavours to show that the Parnell grit 

 overlies conformably the Orakei Bay beds. 



Two years later Mr. A. McKay, Assistant Geologist, 

 wrote a brief account of the coast-line from Lake Takapuna 

 northwards to the Wade, in which he conjectures that the 

 volcanic ash-bed known as the " Parnell grit" is the southern 



